Process of recovering rosin from resinous wood



nited States Patent Ofice Patented July 31, 1956 George H. Cook, Jr., Powder Company, Delaware N Drawing. Application July 9, 1953, Serial No. 367,081

13 Claims. (Cl. 260-110) Brunswick, Ga., assignor to Hercules Wilmington, Del., a corporation of This invention relates to an extraction process and more particularly to an improved method for extracting resinous materials from Wood.

It is known that pine wood may be extracted with a coal tar hydrocarbon such as benzene, and other types of solvents have also been used for this purpose. None of the solvents heretofore, utilized, however, has been entirely satisfactory from an efliciency standpoint, and some of the prior art extraction solvents have had other disadvantages as well. For example, when pine wood is extracted with certain solvents, for example, acetone, and the drop liquor, as the resulting extract solution is called, is evaporated there is formed an insoluble thermosetting precipitate which adheres to the walls of the distillation apparatus, thereby reducing efliciencies and finally necessitating work stoppage for dismantling and cleaning. There has been a need for an extraction process which would permit greater efliciency in removal of resin from wood and which would not have the unfavorable characteristics of the prior art processes.

In accordance With this invention, resin is extracted from pine wood by treating the resinous wood with a ketone containing at least five but not more than nine carbon atoms. The ketone may be acyclic or alicyclic. Exemplary ketones operable in this invention are methyl isobutyl ketone, diethyl ketone, methyl isopropyl ketone, diisobutyl ketone, cyclohexanone, mesityl oxide and acetyl acetone. Of these ketones, methyl isobutyl ketone is outstanding as a pine wood extractant and is the preferred 7 pine wood has not been previously steamed, turpentine and pine oil will also be extracted. The extract solution is then distilled to remove the solvent ketone and then turpentine and pine oil, if present, are also distilled 01f leaving a residue of pine wood resin. The constituents of pine wood resin may be isolated and refined by well known means.

The keytone solvents of this invention represent a substantial improvement over prior art solvents as resinous wood extractants. For example, when acetone is used to extract resin and the extract evaporated to remove acetone, extracting and distilling apparatus constructed of materials customarily utilized are excessively corroded rendering the process commercially unfeasible. Also, evaporation of an acetone extract of pine wood resin results in fouling of distillation apparatus in that an insoluble thermosetting precipitate forms on the walls of the apparatus. As a consequence distillation efiiciency is reduced and dismantling and cleaning is mandatory. Another disadvantage of acetone as a resin extractant arises from the fact that acetone, in addition to removing desirable resins from the resinous wood, also removes many undesirable materials such as sugars, acids, and aldehydes, thereby rendering very diflicult the production of certain products. In contrast, the ketone solvents of this invention do not corrode equipment, do not foul the distillation apparatus by precipitation, and produce typical naval store products.

The extracting power of the ketone solvents of this invention substantially exceeds that of aromatic hydrocarbon solvents. For example, pine wood chips containing 25% water by weight extracted with benzene at 95 p. s. i. g. pressure and 129 C. produced a yield of 422 lbs. resin per ton of wood whereas under similar conditions comparable chips extracted with methyl isobutyl ketone produced 451 lbs. resin per ton of Wood. In some instances, even greater yields have been obtained using certain ketones of this invention and in no instance was the distilling apparatus found to be fouled when the extract solution was evaporated.

Table 1 shows results of extracting pine Wood with ketone solvents of this invention compared with results obtained using benzene:

Table I Analysis of Extract Temper- Y Yield,

Wood Particle Percent ature, Pressure, Solvent lbs. per Batch Size H O 0. p. s. i. g. ton dry Acid Melting Percent wood No. Point, Gasoline, O. Insoluble 2o Atm0spheric. Benzene e25 151 81 11.5 20 20 Inches Hg Cyelohexanone. 661 147 83 172 Vacuum. 55a do 20 85 Atmospherie. Mlezthyl Isopropyl 657 147 81 15.8

i etone.

55a do 20 88 do.. Dietl1ylKet0ne..- 650 150 82 13.9

species of ketone. The extraction process" of this invention produces an increased yield of resin from wood ranging up to 50 lbs. per ton of wood depending upon particular extraction conditions employed and the concentration of resin in the original wood.

In carrying out the process of this invention, pine wood chips, preferably from the Southern long leaf pine in the form of stump wood, root or top wood, are extracted with a ketone such as, for example, methyl isobutyl ketone until extraction is substantially completed. Pine wood may be steamed before extraction with the ketone or the extraction may be carried out without previous steaming of the Wood. .The ketone removes from the pine Wood, rosin and other resinous materials and where the Methyl isobutyl ketone is the preferred species of ketone in this invention because of its substantially superior characteristics as a pine wood extractant. While the other ketones of this invention are markedlysuperior to the best priorv art pine wood extractants, namely commercial practices, it isof 90 C. to C. and' benzene and toluene none possesses all the unique advantages of methyl isobutyl ketone. Because of its relatively high vapor pressure, higher flash point, lower toxicity and greater water solubility as compared with 4 treatment, fresh methyl isobutyl ketone is used as extractant. In this manner, maximum utilization of the extracting power of the ketone is obtained, in that the ketone having the greatest extracting power contacts benzene and toluene, methyl isobutyl ketone represents a 5 wood least rich in resin, and solvent mixture having the great improvement over either of the latter in the exleast extracting power (i. e., being richest in resin) contraction of resin from pine wood. The higher flash point tacts wood richest in resin. By operating in this manner and lower toxicity provide greater safety for operating equilibrium conditions may be maintained and the most personnel. The higher vapor pressure of methyl isobutyl efiicient use of solvent achieved. ketone permits efiicient operation at much lower pressures Although it is preferred to carry out this invention than with prior art solvents. using a ketone of this invention as sole extractant, mix- Because methyl isobutyl ketone is more soluble in tures of these ketones may also be utilized effectively. water than benzene, the practice of this invention differs In addition, the invention may be practiced using a from prior art processes in that there is no necessity for ketone of this invention admixed with a small amount the resinous wood to have a low moisture content. The 0f aIlOther i $11011 as bfinZeIle, acetone, 'EOlueIle, advantages of this invention may be obtained using Wood Pafaifin Y C Q The added Solvent in 511011 containing upwards of 30% moisture content by weight. instances should not be present in greater than minor Usually wood as processed contains from 15 to amounts nor in amounts large enough to diminish submoisture by weight. Notwithstanding the higher moisstantially the desirable attributes of the ketone used. t e o t nt of the wood hi howe er, it h b 20 WhatI claim and desire to protect by Letters Patent is: found that the spent wood, produced as a by-product 1. In the process of recovering rosin from resinous in the process of this invention, has a lower moisture Wood the step comprising extracting the wood with a content than spent wood obtained by prior art processes. ketone Containing at least five but IlOt r a n n The spent wood resulting from the practice of this in- C r on atoms. vention, therefore, is more useful and valuable as fuel. 2 2. In the process of recovering rosin from resinous The ketone solvents of this invention possess higher Wood the p Comprising extracting the Wood With penetrability than prior art solvents such as benzene. ketone Selected from the group Consisting of diethyl This characteristic of the invention permits more comketone, i y P PY ketone, methyl isobutyl ketone, plete extraction of resin and also allows extraction of ii yl k n y h n mesityl i a tyl chips larger-in-size than heretofore possible without loss acetone and mixtures thereof. of yields. Consequently, grinding of chips to the small 3. The process of claim 2 in which the ketone is diethyl size found essential in the art is not necessary and further k n savings in time and labor are effected. The substantially 4. The process of claim 2 in which the ketone is methyl higher penetrability of methyl isobutyl ketone as comi op opyl k tone. pared with benzene is illustrated by the data in Table II. 5. The process of claim 2 in which the ketone is methyl To obtain this data one-inch cubes of a pine wood sample i yl ketone. containing 856 lb./ton resin were extracted at atmos- 6. The process of claim 2 in which the ketone is dipheric pressure under comparable conditions. isobutyl ketone.

Table II Yield, Ein- Wood Particle Size Percent Temp., Press. Solvent lb./t0n eiency, Batch H2O 0. fresh percent wood A 1-in.cube 6 90 Atm0s. MIBK 819 95.7 A do 6 reflux .d0 Benzene 458 53.5

Still another advantage of the process of this invention 7. The process of claim 2 in which the ketone is cycloover prior art processes attaches to the refinability of hexanone. the rosin extracted. Lighter colored rosins are more 8. In the process of recovering rosin from resinous easily attainable when pine wood is extracted with the wood the step comprising extracting the wood with a ketone solvents of this invention. It has been found ketone selected from the group consisting of diethyl that resinous pine wood from certain localities and also ketone, methyl isopropyl ketone, methyl isobutyl ketone, certain types of wood, when extracted with benzene, do diisobutyl ketone, cyclohexanone, mesityl oxide, acetyl not produce light colored rosin products. When this acetone and mixtures thereof at a temperature of 80- same wood is extracted with, for example, methyl iso- 175 C. and a pressure of 0-125 p. s. i. g. butyl ketone, a rosin of a W color can be easily ob- 9. The process of claim 8 in which the ketone is diethyl tained using customary refining techniques. ketone.

The process of the invention can be utilized in either 10. The process of claim 8 in which the ketone is a batch or continuous operation and is suitable for counmethyl isopropyl ketone. tercurrent extraction techniques. In the latter type of 11. The process of claim 8 in which the ketone is operation, a quantity of wood is passed through a nummethyl isobutyl ketone. ber of extraction stages and treated in each stage with, 12. The process of claim 8 in which the ketone is difor example, a portion of methyl isobutyl ketone. The isobutyl ketone. extract solutions are maintained separate from one an- 13. The process of claim 8 in which the ketone is other. The extract solution from stage 1 is directly cyclohexanone. distilled, following removal of any water layer present to recover solvent and resin. The extract solution from Refemnces Cited in the file of this patent stage 2 1S used to extract resins from the fresh batch of wood chips entering stage 1 and the extract solution from UNITED STATES PATENTS each of the remaining stages is used as extractant in each Rs, 19,749 Bent Nov. 12, 1935 of the preceding stages (based on thefiow of wood chips 2,423,020 Haun June 24, 1947 through the operation). In the last stage of wood chip 2,424,628 Palmer July 29, 1947 

1. IN THE PROCESS OF RECOVERING ROSIN FROM RESINOUS WOOD THE STEP COMPRISING EXTRACTING THE WOOD WITH A KETONE CONTAINING AT LEAST FIVE BUT NOT MORE THAN NINE CARBON ATOMS. 